Getting an Uber or a Lyft may be impossible — or take longer and cost more — Wednesday when drivers for both companies plan to strike in major U.S. cities to protest what they say are unfair wages and poor working conditions.

Thousands of drivers in at least eight cities — including Los Angeles, New York and Washington — are planning to shut off their apps and join rallies outside company headquarters and regional offices, according to labor organizers.

It is unclear how the labor action might affect travel, but experts say disruptions are likely in cities where the app-based rides have become a critical mode of transportation. Riders should anticipate surge pricing and longer wait times due to a possible shortage of drivers, they say. In some markets, drivers are asking passengers to support their cause by boycotting the services in cases where drivers are working.

“This is an act of solidarity with drivers across the country, and really across the world, who are suffering with poverty wages,” said Bhairavi Desai, executive director of the New York Taxi Workers Alliance, which is helping organize thousands of drivers in New York.

In preparation for possible service disruptions, some airport authorities said Monday they were urging passengers to plan ahead to use public transportation where available. In the Washington area, officials said they were working with taxi dispatch teams at Reagan National and Dulles International airports to ensure that extra taxis were available in the event of increased demand Wednesday.

“We’ll have extra dispatchers available to help manage any increased crowds in the taxi lines on the curb and ensure that customers can get on their way as quickly and safely as possible,” said Christina Saull, a spokeswoman for the Metropolitan Washington Airports Authority. “At Reagan National, we always encourage passengers to consider using Metrorail as a good alternative to ground transportation — that advice would definitely apply to Wednesday as well.”

There is a Metro stop at National; bus service is available at Dulles. Metro said it is planning to have extra trains and buses on standby in the event of a ridership surge.

The work stoppage is part of a growing national campaign for better wages for the independent contractors who support millions of trips daily in the United States and abroad. The services have become a preferred choice for many travelers in recent years — for daily commutes, trips to and from the airport, and transportation to entertainment and nightlife. As the ride-hailing services have expanded, they also have become critical for public transit agencies in filling service gaps or providing paratransit services.

An Uber spokeswoman declined to speculate on the possible effects of a strike, and Lyft did not respond to a request for comment Monday. In a statement, Uber said: “Drivers are at the heart of our service — we can’t succeed without them — and thousands of people come into work at Uber every day focused on how to make their experience better, on and off the road. Whether it’s more consistent earnings, stronger insurance protections or fully-funded four-year degrees for drivers or their families, we’ll continue working to improve the experience for and with drivers."

The strike was first called by drivers in Los Angeles, who have held protests in recent weeks over a wage restructuring there for Uber drivers, who had their per-mile rates cut by 25 percent. Drivers in other countries, including England, are joining the strike, with some holding daylong work stoppages and others joining only for a few hours.

In New York, as many as 10,000 drivers are joining a two-hour morning commute work stoppage, organizers with the New York Taxi Workers Alliance said. Although New York drivers won a recent battle when the city enacted a law that mandates ride-hail companies pay them at least $17.22 an hour after expenses, organizers said the rates across the board are below a living wage.

“The wages are so unpredictable and so low, it’s very difficult to make a living,” said Henock Wonderse, 40, a Virginia resident who has driven with Uber since 2012. He plans to shut down his Uber operation Wednesday, joining other drivers in the Washington area at an evening rally at National Airport. “We want better pay, and we hope the passengers join us to get that message across."

Besides better wages, drivers are calling for a more transparent wage structure, attention to safety concerns and a right to appeal “unjust firings” with little to no notice. A Georgetown University study of 40 Washington Uber drivers found some thought the work “unsustainable,” with one-third reporting assaults or safety concerns and saying they went into debt to drive on the platform.

Uber has reported that its drivers have earned more than $78.2 billion on the platform since 2015, and $1.2 billion in tips. The company says that it offers financial rewards for qualifying drivers and that drivers can track their earnings in real time. On safety, Uber cites a number of features, including an emergency button, share trip feature and 911 integration technology in more than 40 cities.

But drivers say they can barely make ends meet after expenses such as gas and vehicle maintenance. And many have problems calculating their compensation, said Katie J. Wells, the Georgetown researcher who led the study in Washington. Uber has reduced the base rate that is paid to drivers since it launched and added fees including a “rider safety” fee, she said.

“There are real safety and financial concerns in the workplace,” Wells said.